Replacing soybean meal with extruded urea in rearing steer supplements on supplement intake, weight gain, muscle development and economic performance.

The study aimed to evaluate the effects of supplements containing soybean meal or extruded urea as true protein or non-protein nitrogen sources on supplement intake, performance, and cost of beef steers in the water-dry and water transition. In a completely randomised design, thirty-six Nellore steers with an average of 200 kg body weight (BW) kept in four paddocks, distributed into two treatments with nine animals each. Supplements containing non-protein nitrogen (extruded urea) or true protein (soybean meal) for two seasons were formulated. Data were analysed using ANOVA, with significance set at <italic>P</italic> ≤ 0.05 and trends at <italic>P</italic> ≤ 0.10. Animals fed supplement with true protein had greater supplement intake and greater total dry matter intake, which allowed higher average daily gain (ADG) and final BW. Likewise, during the wet-dry transition period, animals fed true protein had greater intake (total and supplement), ADG, TWG, and final BW. Regarding production costs, the use of soybean meal supplements had higher supplementation costs but also had higher income to animals and area. Despite having lower feed costs, the total replacement is not recommended of true protein by non-protein nitrogen sources in supplements for steers in the growing phase. [ABSTRACT FROM AUTHOR]